The string-to-string correction problem with block moves

Abstract

The string-to-string correction problem is to find a minimal sequence of edit operations for changing a given string into another given string. Extant algorithms compute a longest common subsequence (LCS) of the two strings and then regard the characters not included in the LCS as the differences. However, an LCS does not necessarily include all possible matches, and therefore does not produce the shortest edit sequence. An algorithm that produces the shortest edit sequence transforming one string into another is presented. The algorithm is optimal in the sense that it generates a minimal covering set of common substrings of one string with respect to another. Two improvements of the basic algorithm are developed. The first improvement performs well on strings with few replicated symbols. The second improvement runs in time and space linear to the size of the input. Efficient algorithms for regenerating a string from an edit sequence are also presented. © 1984, ACM. All rights reserved.